Naval radar systems search space using a plurality of sequential directional beams which may be pointed in a given direction. In general, an acquisition face to be searched is defined, and radar beams are directed to cover the entire face. This type of searching is subject to time constraints, as the beam must dwell at a particular beam angle long enough for the transmitted radar signals or pulses to travel to the target and for the reflection to return to the radar.
When another source such as a cooperating radar develops information about the possible presence of a target in a given direction or location, it may be desired to examine a volume about the nominal given direction in an attempt to acquire the target. This is referred to as a “cued” search. If the selected volume is too large, the search may time-out before completion. But if the selected volume is too small, the target might not be found.
In general, methods are known for searching a search volume about a given cued direction and with a given maximum search range. The search of a designated volume is, as noted, performed with sequentially generated radar beams. Such methods may involve acquiring the nominal track position and velocity (i.e., cue information) and time, as well as error information describing the uncertainty in the cue information. Error may be represented by a covariance, and may be presented together with the cue information, and from this information, azimuth and elevation extents (the acquisition or search face) of the search volume are determined.
Given that searching is subject to time constraints, as noted above, it is desirable to provide the most accurate practical calculation of the cued acquisition volume possible, while minimizing the computational complexity of the process. Thus, there is a need for a computationally simple technique for providing a best possible estimate of an acquisition search volume. Such a technique should minimize the total time require to search a volume while maximizing the likelihood that the volume contains the target object.